Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session G6: Precision Measurements and Tests of Basic Physics |
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Chair: Subhadeep Gupta, University of Washington Room: Garden 4 |
Wednesday, June 6, 2012 8:00AM - 8:12AM |
G6.00001: Atom Interferometry with Bose-Einstein condensates to measure $\alpha$ Alan Jamison, Ben Plotkin-Swing, Anders Hansen, Alexander Khramov, Will Dowd, J. Nathan Kutz, Subhadeep Gupta The most precise measurement of the fine structure constant, $\alpha$, comes from the electron $g-2$ measurement. This result relies on high orders of perturbation theory in QED. A complementary measurement of $\alpha$ with less dependence on theory would allow for extremely stringent tests of QED. Atomic recoil measurements, which measure $h/m$ for a given atomic species, are a promising direction for such a measurement. We will report on our progress toward a Bose-Einstein condensate (BEC) interferometer to measure the atomic recoil of ytterbium (Yb) with high precision. Use of a BEC allows for long interrogation times and a robust signal. Using Yb eliminates magnetic fields as a potentially damaging systematic while allowing comparison of results for different isotopes. We have established key components of the interferometer with a $^{174}$Yb BEC: diffraction with short laser pulses for momentum-state beam-splitting and with long pulses as mirrors. We are working on acceleration pulses to achieve large momenta in the different interferometer arms, necessary for a sub-ppb measurement of $\alpha$. [Preview Abstract] |
Wednesday, June 6, 2012 8:12AM - 8:24AM |
G6.00002: Precision Atomic Masses of Calcium, Strontium and Ytterbium Edmund Myers, Raman Rana, Martin Hoecker Currently the second most precise value for the fine structure constant is derived from ``photon-recoil'' measurements of h/M(Rb) combined with the Rydberg constant, atomic transition frequencies, and the atomic masses of the electron and rubidium. An improved photon-recoil value for alpha will enable the combination of theory and experiment for the g-factor of the electron, which produces the most precise value for alpha, to provide an improved test of QED. Besides the alkalis, isotopes of the alkaline-earths and ytterbium can make promising candidates for precise photon-recoil measurements of h/M(atom). In addition, the mass of 40Ca is required for obtaining the g-factor of hydrogen-like calcium from measurements of electron spin-flip and cyclotron frequencies of Ca19+, which would provide a test of bound-state QED theory. For these and other applications, we have now measured cyclotron frequency ratios of pairs of ions in a cryogenic Penning trap that should yield the atomic masses of 40Ca, 86,87,88Sr, and 170,171,172,173,174,176Yb to a precision of $\sim$0.2 ppb. [Preview Abstract] |
Wednesday, June 6, 2012 8:24AM - 8:36AM |
G6.00003: Polarizability measurements of alkali atoms using an atom interferometer Ivan Hromada, William Holmgren, Raisa Trubko, Alexander Cronin We present our latest static polarizability measurements of the alkali atoms Li through Cs. Our measurements rely on a gradient electric field region in our atom interferometer. We have demonstrated 0.1\% precision in polarizability and 0.05\% precision in atom beam velocity measurements. Because we use the same apparatus to measure the polarizabilities of different atomic species, we are able to report polarizability ratios (e.g., $\alpha_{Cs}$/$\alpha_{Li}$) with similar precision. We discuss the systematic errors that limit the precision of our absolute and ratio measurements. These measurements provide benchmark tests of complex atomic structure calculations needed for atomic clocks and parity non-conservation experiments. [Preview Abstract] |
Wednesday, June 6, 2012 8:36AM - 8:48AM |
G6.00004: Model independent analysis of proton structure for hydrogenic bound states Gil Paz The charge radius of the proton is a basic non-perturbative parameter. Recently, it was extracted for the first time from the Lamb shift in muonic hydrogen. For a long time it was anticipated that such a measurement would reduce the error by an order of magnitude compared to measurements from electron- proton scattering and regular hydrogen spectroscopy. While this goal was achieved, the value of the proton's charge radius that was obtained was, very surprisingly, five standard deviations away from the world average. The extraction of the charge radius from the Lamb shift in muonic hydrogen depends on a theoretical input. Together with Richard J. Hill, we are studying the hadronic uncertainty in the theoretical prediction using the tool of an effective field theory, namely NRQED. In the talk I will describe the results of this study. [Preview Abstract] |
Wednesday, June 6, 2012 8:48AM - 9:00AM |
G6.00005: Nuclear and QED corrections to the bound-electron $g$ factor Jacek Zatorski, Natalia S. Oreshkina, Christoph H. Keitel, Zolt\'an Harman We calculate nuclear shape and quantum electrodynamic corrections to the $g$ factor of a bound electron~[1,2]. These theoretical studies are motivated by the current improvement of experimental possibilities: on the one hand, in a recent Penning trap measurement~[2], the $g$ factor of $^{28}\rm{Si}^{13+}$ has been determined with an unprecedented $5 \cdot 10^{-10}$ relative uncertainty. A novel experimental technique will further improve accuracy to the $10^{-11}$ level. On the other hand, experiments with ions as heavy as $^{238}\rm{U}^{91+}$ will be performed soon at the HITRAP-FAIR facility. For such heavy ions, nuclear effects play an important role. The leading relativistic nuclear deformation correction has been derived analytically and also its influence on one-loop quantum electrodynamic terms has been evaluated. We present results for medium- and high-$Z$ hydrogenlike ions, which become significant already for mid-$Z$ ions, and for very heavy elements it even reaches the $10^{-6}$ level, as we show in~[1].\\[4pt] [1] J.~Zatorski, N.~S.~Oreshkina, C.~H.~Keitel, and Z.~Harman, Phys. Rev. Lett., in press; arXiv:1110.3330 \newline [2] S.~Sturm, A.~Wagner, B.~Schabinger, J.~Zatorski, \textit{et al.}, Phys. Rev. Lett. \textbf{107}, 023002 (2011). [Preview Abstract] |
Wednesday, June 6, 2012 9:00AM - 9:12AM |
G6.00006: Measuring the atomic recoil frequency with a grating-echo atom interferometer Brynle Barrett, Adam Carew, A. Kumarakrishnan We discuss progress toward a precise measurement of the atomic recoil frequency using a grating-echo atom interferometer. Large laser-cooled samples of $^{87}$Rb with temperatures as low as 2.4 $\mu$K have been achieved in a new experimental apparatus with a well-controlled magnetic environment. We have realized interferometer signal lifetimes approaching the transit time limit in this system ($\sim 270$ ms), which is comparable to the timescale of Raman interferometers. The measurement technique involves exciting the sample with three chirped standing wave pulses, and mapping out the contrast of an atomic density grating as a function of the third pulse time. The signal exhibits narrow fringes that are separated by measurement timescales of $\sim 50$ ms. This interferometer can also be used for sensitive measurements of magnetic field gradients and gravitational acceleration [B. Barrett \textit{et al}, Phys.~Rev.~A \textbf{84}, 063623 (2011)]. [Preview Abstract] |
Wednesday, June 6, 2012 9:12AM - 9:24AM |
G6.00007: Towards optical pumping of ytterbium nuclei embedded in a solid neon matrix Chen-Yu Xu, Jaideep Singh, Kevin Bailey, Zheng-Tian Lu, Peter Mueller, Thomas O'Connor We have studied the optical excitation and decay dynamics of neutral ytterbium atoms embedded in a cryogenic solid neon matrix. Matrix isolated atoms qualitatively retain the energy level structure of atoms in the gas phase. The transitions are typically blue shifted and significantly broadened to a few hundred cm$^{-1}$, independent of temperature from 2.6 K to 4.2 K. The transition width is found to be homogeneous but not lifetime broadened. We will report our results on spectroscopy, lifetimes, and our attempt to polarize nuclear spins by optical pumping. Applications of such a technique include studies of rare isotopes and tests of fundamental symmetries. This work is supported by DOE, Office of Nuclear Physics, under contract DEAC02-06CH11357. [Preview Abstract] |
Wednesday, June 6, 2012 9:24AM - 9:36AM |
G6.00008: Investigation for the Macroscopic Quantum Electrodynamics to describe light in dielectric material Moochan B. Kim, Tae-woo Lee, Georgios Veronis, Hwang Lee, Jonathan P. Dowling Though the behavior of photons in medium can be easily formulated in usual microscopic Quantum Electrodynamics, the presence of matter makes this dicult to describe due to nontrivial degrees of freedom of matter. Alternative approach is to begin with macroscopic Maxwell's equation including a dielectric material. It may be useful to predict the behavior of the system. Until now, a few theories for macroscopic QED was suggested without a confirmation. To discern the proper description for the system, we investigate and suggest experiments for a simple optical interferometer, such as the Hong-Ou-Mandel and Mach-Zehnder interferometers, which may be made in integrated dielectric materials. [Preview Abstract] |
Wednesday, June 6, 2012 9:36AM - 9:48AM |
G6.00009: Enhanced Sensitivity in a Superluminal Single Mode DPAL Cavity at Room Temperature Tony Abi-Salloum, Joshua Yablon, Shih Tseng, Selim Shahriar The note beat between two counter-propagating beams in a cavity is used to measure the effective change of the length of the cavity or interferometer for applications such as optical gyroscopes, vibrometers, and gravitational wave detectors. We show in this talk how a superluminal single mode laser cavity can enhance the measured note beat dramatically. We consider the inhomogeneous broadening case and study the dependence of the enhancement factor on few key parameters. We also show how Diode Pump Alkali Lasers (DPAL) are excellent candidates for such devices. Using a Rubidium based DPAL, we study the characteristics of these lasers and their effect on the proposed enhanced sensitivity. [Preview Abstract] |
Wednesday, June 6, 2012 9:48AM - 10:00AM |
G6.00010: Precise measurements of microwave transitions in CH with high sensitivity to variation of fundamental constants Stefan Truppe, Richard Hendricks, Sean Tokunaga, Edward Hinds, Michael Tarbutt Recent calculations [1] show that the Lambda-doublet transitions of certain diatomic molecules are highly sensitive to possible variations of the electron-to-proton mass ratio and the fine structure constant. The lowest-lying Lambda-doublets of the CH molecule are particularly sensitive and can be observed in astrophysical objects at high red-shift, offering a precise test of variations in these fundamental constants over billions of years, without needing reference lines from other species. To improve the current laboratory measurements of these microwave transitions, we have developed a cold beam of CH radicals and have measured the transition frequencies to high precision using the Ramsey method of separated oscillatory fields.\\[4pt] [1] M.G. Kozlov, \textit{``Lambda-doublet spectra of diatomic radicals and their dependence on fundamental constants''}, Physical Review A \textbf{80}, 022118 (2009) [Preview Abstract] |
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